Transferring photos from Ipad

I am putting together a book which will include watercolors and sketches I have made. These are done on pages of varying sizes. When I’m done, I take a photo and store them on my IPad. When it comes time to publish my book, will the size of the paper I’ve been using matter? In Photos on the IPad, they all look fine. But when I transfer these to the book I make, is there anything I should take into account?